Could stress really have made Sarah Palin's hair fall out?

Answers to your questions about the news.
July 13 2009 6:23 PM

Can Stress Really Make Your Hair Fall Out?

You betcha!

Bald man. Click image to expand.
Does stress cause thinning hair?

Nosy tabloids, an endless stream of ethics complaints, and opposition to her legislative agenda caused Sarah Palin so much stress that her hair thinned dramatically, according to an account published in the New York Times. Can stress really cause hair loss?

Yes. Studies on both laboratory mice and disembodied human hair follicles have shown that external stresses can cause hair loss. Researchers have exposed otherwise healthy mice to mouse-repelling sounds at 15-second intervals for 24 hours. The follicles of the stressed mice went dormant significantly faster than their more relaxed cousins. No such experiment has been conducted on people, but scientists do know that if you expose human hair follicles to substance P, a stress-related neurochemical, they will also become dormant.

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Clinically speaking, the most common form of stress-induced hair loss is telogen effluvium, a thinning-out of the hair that comes about when follicles go into a prolonged resting phase. Under normal circumstances, a single strand of hair emerges from a scalp follicle during the anagen phase and proceeds to lengthen for a period of about three years. During the transitional catagen phase, the hair stops growing and the follicle tightens around the strand. Finally, the follicle enters the telogen, or resting, phase, for three months of dormancy before it sheds the strand of hair and starts the cycle anew. At any given time, about 10 percent of your scalp follicles should be in this resting phase—but that proportion can be much higher in telogen effluvium sufferers. This doesn't show up as baldness or hair-thinning until several months later, when all the resting follicles finally shed their hairs and restart the cycle.  

In addition to garden-variety stress, telogen effluvium can be caused by pregnancy, medication, malnutrition, renal dialysis, or hypothyroidism. The condition usually resolves without treatment within a few months, although rare cases of permanent hair loss have been reported.

(Bored at work? You can easily identify the phase of your own plucked hair. Any strand with a round, white bulb on the end was in the telogen phase. Anagen hairs, on the other hand, usually break along the shaft, leaving the follicular tissue behind.)

Another cause of periodic hair loss is alopecia areata, in which white blood cells attack the hair follicles, leaving bald patches. Like arthritis or multiple sclerosis, it's an autoimmune disorder in which the body's defenses against invaders erroneously attack normal cells. The causes of the disease are not well-understood, but studies have suggested that some people are genetically predisposed to the condition, which often manifests during times of stress. It tends to emerge in childhood and recur periodically, so, unless she has a history, Palin probably won't develop it. Alopecia areata is usually treated with topical or injected steroids.

If Palin's hair really is thinning, there's a third possible explanation: Female androgenetic alopecia, or female pattern baldness. This condition—characterized by thinning of hair throughout the scalp, but especially on the crown—results not from stress but rather from hormonal changes typical of menopause. (While 10 percent of women suffer from the condition during their youth, almost 75 percent develop it during menopause.) Although the average American woman does not face menopause until turning 51, Palin, at 45, is within the normal range. Female androgenetic alopecia can be treated with minoxidil (Rogaine), but the drug only works in about one-fifth of all cases. For most, thinning hair is irreversible.

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Brian Palmer is Slate's chief explainer. He also writes How and Why and Ecologic for the Washington Post. Email him at explainerbrian@gmail.com. Follow him on Twitter.